It is known to provide lead frames in strip form and to connect bonding pads on a chip on which a circuit has been deposited to inner ends of corresponding leads of the lead frame, and then to place the chip, the inner ends of the lead frame and the connections thereto into the molding cavity and to force fluid encapsulating material into the mold cavity, thereby filling the cavity and encapsulating the chip, the inner ends of the lead frame and the connections thereto. In doing this in accordance with the prior art, a gateway in the mold is provided for the cavity for the entry thereinto of fluid encapsulating material and the gateway is connected by a feed runner to a main runner. The main runner is connected to a reservoir into which the encapsulating material is placed and liquified by applying heat thereto and a piston is forced into the reservoir to force the fluid through the main runner, through the feed runners and through the gates into the several cavities formed in the mold. The provision of the feed runners and gates complicates the construction and maintenance of the mold. Furthermore, in the prior art the main runner runs alongside the strip frame and to one side thereof whereby the feed runners are quite long since each thereof runs about half-way across the lead frame from the main runner to the cavities. Each time a mold is used, the cavities thereof and the main and feed runners must be cleaned out, since a clogged runner will prevent the cavity from being filled with encapsulating fluid, resulting in a reduced yield of properly encapsulated semiconductor devices.
It is an object of this invention to provide a lead frame, which may be provided in the form of a strip of lead frames, which do not require feed runners or gates in the mold when the inner ends of the lead frames are encapsulated as part of an encapsulated semiconductor device.
It is another object of this invention to provide the combination of a lead strip and a mold requiring no feeder runners or gates in the mold.